Police said they received a 911 call about drug activity on the steps of a building in the 7800 block of South Cregier Avenue shortly after 10:45 p.m., and when two tactical unit officers arrived, three men at the address fled. An officer chased the man through an alley and into a parking lot, Camden said. The man appeared from behind a parked car and fired at the officer, Camden said. The officer, who was not hit and did not have his weapon drawn, began retreating, then tripped and fell, Camden said.

The man -- identified by the Cook County medical examiner's office as Samuel Holmes, of an unknown address -- then fired two more rounds at the officer, missing, before the officer drew his weapon and returned fire, Camden said.

The unidentified man was taken to Advocate Christ Medical Center in Oak Lawn, where he was pronounced dead on arrival, Camden said.

Police have not named the officer who fired the shots or his partner, but said the officer was not injured during the incident, which is under investigation by the Police Department's Office of Professional Standards.

Police recovered a .38-caliber revolver at the scene, Camden said.

Camden said the officer was fortunate to have not been injured by the gunfire directed at him. He said the officer could have "a guardian angel with him."